The Campeonato Brasileiro Série A (Brazilian Portuguese: ), commonly referred to as Campeonato Brasileiro and popularly as Brasileirão (Brazilian Portuguese: ), is a Brazilian professional league for men's association football clubs. At the top of the Brazilian football league system, it is the country's primary football competition. Contested by 20 clubs, it operates on a system of promotion and relegation with the Campeonato Brasileiro Série B.

Organized by the Brazilian Football Confederation, the seasons are usually run from May to December, with teams playing 38 matches each (playing each team in the league twice, home and away) totalling 380 matches in the season. The league rounds are usually played in Sunday afternoons and Wednesday evenings. It is currently sponsored by Chevrolet and thus officially known as the Brasileirão Chevrolet.

Due to historical peculiarities and the large geographical size of the country, Brazil has a relatively short history of nationwide football competitions. Only in 1959, with the advancements in civil aviation and air transport and the need to appoint a Brazilian representative to the first edition of the Copa Libertadores in 1960, was a nationwide tournament created, Taça Brasil. Before the establishment of a national league, the most prestigious football competitions in Brazil were the state leagues, notably the Campeonato Paulista and Campeonato Carioca, the premier leagues of the States of São Paulo and Rio de Janeiro respectively, and a tournament between both states, the Torneio Rio-São Paulo. In 1967, the Rio-São Paulo was expanded to include teams from other states, becoming the Torneio Roberto Gomes Pedrosa, which was also considered a national tournament. The first Campeonato Brasileiro with that name was held in 1971. The three tournaments - Taça Brasil, Roberto Gomes Pedrosa, and Brasileirão - were unified by CBF in the Brazilian championship history in 2010.

Since its inception, the Campeonato Brasileiro has grown in stature, being considered one of the strongest leagues in the world. The Campeonato Brasileiro contains the most club world champions titles, with 10 championships won among 6 clubs. The league also contain the most clubs to have won the Copa Libertadores with 17 titles won among 10 clubs. The league is also one of the world's most powerful, ranked as the 6th most valuable with a worth of over $1.43 billion. It is also one of the world's richest championships, generating an annual turnover of over $1.169 billion in 2012. The Campeonato Brasileiro is the most-watched football league in the Americas and one of the world's most exposed, broadcast in 155 nations.

Since 1959, a total of 17 clubs have been crowned Brazilian football champions, 12 of which have won the title more than once with 6 having won the title in consecutive seasons. Santos and Palmeiras are the most successful clubs of the Campeonato Brasileiro, having won the competition 8 times each. Santos' Os Santásticos, considered by some the best club team of all times, won 5 consecutive titles between 1961 and 1965, a feat that remains unequaled until today. The State of São Paulo is the most successful state, amassing 28 titles among 5 clubs. A total of 156 clubs have played in the Campeonato Brasileiro since the first edition in 1959.

The reigning Brazilian champions are Cruzeiro, who won their 4th title during the 2014 season.